Question

我的程序运行并编译。但是，我没有得到所需的输出。它输出所有需要的信息，但它也打印出一些我不喜欢的东西。与赞助人，作者和书籍一起，印刷了很多真/假的陈述：

/*true (Current out print statement)
true
true
true
Name: Ken Lambert
Title:  Cider House Rules
Author: John Irving
Title:  The Perfect Storm
Author: Sebastian Junger
Title:  The Illiad
Author: Homer
Title:  Hamlet
Author: William Shakespeare
true
false
false
Name: Ken Lambert
Title:  The Perfect Storm
Author: Sebastian Junger
Title:  The Illiad
Author: Homer
Title:  Hamlet
Author: William Shakespeare (Current Print Statement)


Name: Ken Lambert (Desired print statement)
Title:  Cider House Rules
Author: John Irving
Title:  The Perfect Storm
Author: Sebastian Junger
Title:  The Illiad
Author: Homer
Title:  Hamlet
Author: William Shakespeare

Name: Ken Lambert
Title:  The Perfect Storm
Author: Sebastian Junger
Title:  The Illiad
Author: Homer
Title:  Hamlet
Author: William Shakespeare*/




public class Book
{
 private String author, title;

   public Book(String t, String a){
      author = a;
      title = t;     }

   public String getAuthor(){
      return author;       }

   public String getTitle(){
      return title;   }

   public String toString(){
      return "Title:  " + title + "\n" +
             "Author: " + author;  } 
 }
public class LibraryTester{

   public static void main (String[] args){
      Patron p = new Patron("Ken Lambert");
      Book b1 = new Book("Cider House Rules", "John Irving");
      Book b2 = new Book("The Perfect Storm", "Sebastian Junger");
      Book b3 = new Book("The Illiad", "Homer");
      Book b4 = new Book("Hamlet", "William Shakespeare");

      System.out.println(p.borrowBook(b1));
      System.out.println(p.borrowBook(b2));
      System.out.println(p.borrowBook(b3));
      System.out.println(p.borrowBook(b4));

      System.out.println(p);

      System.out.println(p.returnBook("Cider House Rules"));
      System.out.println(p.hasBook("Cider House Rules"));
      System.out.println(p.hasBook("The Perfect Storm"));

      System.out.println(p);
   }

}
public class Patron{

Book b1, b2, b3, b4;
private String name;

    public Patron(String nm){
    name = nm;
    b1 = null;
    b2 = null;  
    b3 = null;
    b4 = null;
    }
    public String getName(String nm){
    if(name.equals(null))
        System.out.println("You must put in your name!");
    else
        name = nm;
        return name;
    }
    public boolean borrowBook(Book bbook){
    boolean test = false;
    if (b1 == null){
        b1 = bbook;
        test = true;
    }
    else if (b2 == null){
        b2 = bbook;
        test = true;
    }
    else if(b3 == null){
        b3 = bbook;
        test = true;
    }
    else if(b4 == null){
        b4 = bbook;
        test = true;
    }
    else 
    {
        test = false;
    }
    return test;
    }
    public boolean hasBook(String title){
    if(b1 != null)
        if(b1.getTitle().equals(title)){
        return true;
    }
    else if(b2 != null)
        if(b2.getTitle().equals(title)){
        return true;
    }
    else if(b3 != null)
        if(b3.getTitle().equals(title)){
        return true;
    }
    else if(b4 != null)
        if(b4.getTitle().equals(title)){
        return true;
    }

    return false;   
    }
    public boolean returnBook(String b){
    if(b1.getTitle().equals(b)){
        b1 = null;
        return true;
    }
    else if(b2.getTitle().equals(b)){
        b2 = null;
        return true;
    }
    else if(b3.getTitle().equals(b)){
        b3 = null;
        return true;
    }
    else if (b4.getTitle().equals(b)){
        b4 = null;
        return true;
    }
    else
    {
        return false;
    }   


    }
    public String toString(){
    String str = "Name: " + name;
        if(b1 != null)
            str = str + "\n" + b1;
        if(b2 != null)
            str = str + "\n" + b2;
        if(b3 != null)
            str = str + "\n" + b3;
        if(b4 != null)
            str = str + "\n" + b4;
        return str;
    }
}//class

Answer 1

方法public boolean borrowBook(Book bbook)返回一个布尔值。由于你打印了方法的返回，它会打印出......布尔！

  System.out.println(p.borrowBook(b1));
  System.out.println(p.borrowBook(b2));
  System.out.println(p.borrowBook(b3));
  System.out.println(p.borrowBook(b4));

Answer 2

它打印所有这些＆＃34; True / False＆＃34; s因为您使用的方法返回布尔值。

布尔返回语句（使其不打印为true / false）

2 个答案: